1. Field of the Invention:
The invention relates to powered vehicles that direct cooling system outlet air onto the exterior surface of a muffler enclosed within an enclosure or hood.
2. Description of the Related Art:
Conventional vehicles such as lawn and garden tractors are provided with a power source such as an engine or motor, and a cooling system for preventing the power source from overheating. Mufflers are provided for deadening the sound of the engine. It is known to provide hoods for enclosing the engine, cooling system and muffler. However, heat can build up within the hood since the hot muffler, whose exterior surface can reach 700.degree. C., is positioned inside the hood. This buildup of heat can cause the carburetor to experience "vapor lock" and malfunction, or cause the engine to overheat.
Such conventional vehicles fall generally within two categories. The first category provides a water-cooled system, and the second category provides an air-cooled system.
Water cooled systems utilize cool air drawn in from outside the hood to cool a supply of water, and the water then cools the engine. The air that has become warmed within the cooling system is then discharged through an outlet into the chamber of the hood. The outlets of water-cooled systems are typically positioned above the engine. Many vehicles having water-cooled engines allow the cooling system outlet air, which is typically 60.degree. C., to exit the hood through a grille. The mufflers on these vehicles are often partially exposed and not entirely confined within the hood. The mufflers are thereby cooled by the exposure to outside air. However, many such mowers allow the heat created by the exterior surface of the muffler to otherwise accumulate within the hood. Therefore, the heat can back up toward the carburetor and cause engine failure. Further, since many of these mufflers are at least partially exposed, there is a greater likelihood that a bystander could be harmed by contact with the hot exterior surface of the muffler.
The second category of vehicles are air-cooled. Air is drawn in from outside of the hood and used to directly cool the engine. Once warmed by the engine, the warm cooling system air is discharged through an outlet and into the chamber defined by the hood. Air-cooled system outlets are typically located beneath the engine. It is known to deflect this outlet air upwardly toward the muffler and through a grille. Since the air gets very hot as it passes over the muffler, the grille through which the hot air travels must be capable of withstanding high temperatures. Therefore, such grilles have been made of a variety of metals or aluminum, and are relatively costly to manufacture and install. Plastic grilles are generally not capable of withstanding the high temperatures created by the air that has passed over the muffler.
Conventional grilles also serve as a passage through which ambient air can enter and exit so that the engine compartment is further cooled. Typical grilles prevent operators and bystanders from reaching inside of the enclosure and being harmed by the hot power source components or the muffler. The grilles further prevent branches and other obstacles from entering the enclosure and damaging power source components.
Typical vehicles within both of the above categories direct the air upwardly through the grille such that the hot air does not contact the ground. This prevents scorching or damaging the grass or vegetation.
Many small vehicles are manufactured having ballast weights attached to the frame of the vehicle. These weights act to generally enhance the balance of the vehicle when implements are attached.
Therefore, it would be desirable to provide a powered vehicle with a muffler contained within an engine enclosure, and a mechanism for directing cooling system outlet air across the exterior surface of the muffler. It would also be desirable to provide a mechanism for directing the air that has passed over the muffler out of the enclosure through an opening other than the grille, such that the grille is not subjected to high temperatures. The grille could thereby be made out of a plastic material that is more attractive and relatively inexpensive to manufacture. It would be desirable for the opening to be shaped and positioned in such a way that it would be difficult for a person to reach into the opening and be burned by the muffler or engine components. It would be desirable for such a mechanism to be simple and compact in construction, and to utilize components already included on the vehicle that have other functions, such that a separate more costly conduit structure is not required. It would also be desirable for such a mechanism to be relatively compact such that it is compatible with an engine enclosure within which there is only a limited amount of space. Further, it would be desirable for such a mechanism to direct the air out of the enclosure with a horizontal or upward trajectory such that vegetation beneath the vehicle is not damaged.